BLD: Get site-packages dir in a backwards compatible way
BLD: Get site-packages dir in a backwards compatible way

Author: Phillip Cloud <cpcloud@gmail.com>

Closes #1369 from cpcloud/fix-sp-dir and squashes the following commits:

a7747a5b [Phillip Cloud] BLD: Get site-packages dir in a backwards compatible way

cpcloud/ibis,deepfield/ibis,deepfield/ibis,ibis-project/ibis,ibis-project/ibis,cpcloud/ibis,deepfield/ibis,ibis-project/ibis,cpcloud/ibis,cloudera/ibis,cpcloud/ibis,ibis-project/ibis,cloudera/ibis,deepfield/ibis,cloudera/ibis